You can register a 50cc scooter, like any other engine size, at the Department of Land Transport. Most 50cc scooters you “currently” can find in Thailand are powered by a two-stroke engine, trying to register a two-stroke engine is extremely difficult. Also with the strict Thai emission rules trying to register a modern 50cc 4-stroke scooter is not easy. First the scooter needs to pass the Thai emission standard, testing exhaust emission costs more than 30,000 THB.

Also 50cc has no legal benefits, in Thailand everybody younger than 18 years can ride a scooter (with an engine size not exceeding 110cc) without a drivers license.

With the extra cost of 30,000 THB for the emission testing most people who are looking for a cheap scooter buy a 110cc from one of the leading manufacturers.